An image forming apparatus adopting the electrophotographic method transfers an image formed on a photoreceptor drum onto a sheet, and then heats and presses the sheet to fix the toner image on the sheet. In the image forming apparatus adopting the electrophotographic method, toner should be supplied when toner is used up. For this reason, the image forming apparatus adopting the electrophotographic method is generally configured to use a replaceable toner cartridge in which expendable toner is stored.
A toner cartridge includes a stirring paddle for stirring the toner stored in the toner storage container. The stirring paddle keeps a constant mixture ratio of a toner component to a carrier component of the toner stored in the toner storage container and prevents the solidification of toner (for example, refer to JP-A-2006-284776).
Usually, the stirring paddle is manually assembled to a toner storage container having a substantially rectangular shape. A supporting portion of the toner storage container supporting one end of a rotating shaft of the stirring paddle is located at a longitudinal end of the toner storage container. It is difficult for an assembly personnel to observe the supporting portion of the toner storage container thus configured. So that the assembly personnel has to find the supporting portion by pushing one end of the rotating shaft against the end of the toner storage container. If the assembly personnel has a trouble finding the supporting portion, the assembly operation takes longer time, degrading productivity. Such problem is not particular to a toner cartridge. Similar problem may arise, such as, for a cleaner unit collecting toner remaining on a photoreceptor drum or an intermediate transfer belt.